-- Lab submissions: files stored on disk, one row per submission attempt.

CREATE TABLE submissions (
    id         uuid PRIMARY KEY DEFAULT uuidv7(),
    student_id uuid    NOT NULL,
    lab_id     uuid    NOT NULL,
    seq        integer NOT NULL,
    created_at timestamptz NOT NULL DEFAULT now(),
    CONSTRAINT submissions_seq_unique UNIQUE (student_id, lab_id, seq)
);

CREATE INDEX submissions_lab_idx ON submissions (lab_id);